The invention relates to a structural element, comprising two cover layers arranged substantially parallel to one another and a closed frame structure which is formed integrally with the cover layers and is arranged between said cover layers such that a gastight cavity is formed, said cavity containing a vacuum. It also relates to a method for producing a structural element of this type and to a building and a method for equipping said building. Structural elements and methods of this type are known, for example, from WO 2006/003199 A1.
One of the most important challenges for the future is to drastically reduce the consumption of raw materials. Particularly in the construction sector, considerable potentials remain unused both for future and for existing projects. This relates to both the consumption of energy through use, and to grey energy which is associated with the construction, maintenance and demolition of buildings. A further challenge is to gain renewable energy economically, as far as possible without competing against foodstuff production and nature conservation, and to make it storable.
In respect of the energy consumed through use of the building, focus has recently been aimed at improving heat insulation. With regard to consumed energy, particularly in construction, lightweight construction methods are being used. In both areas, attempts are being made here to use vacuum technology.
According to the prior art, in vacuum insulation panels (VIP) and vacuum insulation sandwich panels (VIS), a supporting core of fumed silica, mineral fibres or of other open-pore insulating materials is used which makes it possible to prevent the conduction of the latent heat of gas under relatively high residual pressures. As a result, long-term safeguarding of the vacuum in the panels should be allowed, with relatively low demands being imposed on the sheath. To maintain a high vacuum, the edges in particular of the panels would have to be configured with permeation-tight stainless steel, for example, which, compared to aluminised foil for example, would produce a greater heat conduction over the edge regions. The achievable U value would thereby be higher, particularly in the case of relatively small panels, compared to foil-sheathed VIPs.
However, in the case of vacuum insulation glazing (VIG), it is necessary to achieve a high vacuum since only small spacers, which must not obstruct the transparency, are fitted. Here, the particular challenge lies in the edge join which has to combine a minimal conduction of heat with maximum diffusion impermeability and a slightly flexible behaviour. Likewise, the ratio of volume to surface is problematic for the achievement and maintenance of the high vacuum and requires a very clean working as well as a superior cleaning of the surfaces before they are joined together.
Common to all the vacuum insulations which have been mentioned above and which correspond to the prior art is the fact that they are not produced on site in a construction process and are not adapted in size. Apart from a few exceptions (for example VIS by Thyssen Krupp), a subsequent evacuation is not possible, i.e. in the event of damage and loss of vacuum, the insulating effect is reduced to a minimum which, for example in the case of VIPs, corresponds to the current legal minimum standard in Germany (for VIG, a loss of vacuum implies virtually the complete loss of the insulating effect).
The desired service life of vacuum insulations of at least 20 to 50 years should correspond to the period of use of buildings. To protect VIPs from damage, they are integrated to some extent into (finished) structural elements. Consequently, however, a subsequent replacement upon loss of vacuum and checking the functionality of the insulating effect is relatively complex and, in addition to the high costs, contributes to the limited popularity of this technique.